This invention relates to an automatic molten metal injector for poring molten metal into a mold for e.g. sand mold casting.
One of such injectors is disclosed in Japanese patent publication 8-47765 which was filed by the applicant of the present invention.
This injector is mounted in a furnace holding molten metal, and comprises a sheath, a rotary cylinder received in the sleeve, and a piston vertically slidably received in the cylinder. The cylinder is formed at one end with a port adapted to communicate with the interior of the furnace when the cylinder is rotated to a first position, and to communicate with a mold through a discharge chamber in a second position. With the cylinder rotated to the first position, the piston is raised to suck molten metal into the cylinder through the port. The cylinder is then rotated to the second position, and the piston is lowered to discharge a predetermined amount of the molten metal in the cylinder into the mold through the discharge chamber.
Since the material is fed in a molten state, there is no possibilility of explosion even during magnesium die casting. Since the injector is mounted in the furnace, it is possible to reduce the size of the entire device, minimize the loss of energy and reduce the volume, and shorten the molten metal holding time. This in turn makes it possible to reduce the production of sludge oxides.
With this injector, since communication between the interior of the furnace and the molten metal discharge chamber is controlled by rotating the cylinder, while the cylinder is rotated, the cylinder, sleeve and piston tend to get worn rather severely. This shortens the life of the injector.
An object of the invention is to provide an automatic molten metal injector having no rotary frictional parts yet is still sufficiently durable.